Back door, and glass antenna
View Patent ↗The present invention provides a back door and a glass antenna capable of achieving an inexpensive antenna in which external components can be reduced. The present invention relates to a back door and a glass antenna, in which no choke coil which blocks a signal of a first frequency band between a body of a vehicle and a defogger is provided.
1. A back door made from resin to be openably and closably attached to a rear portion of a vehicle, the back door comprising a glass antenna,
wherein the glass antenna comprises:
a defogger comprising a plurality of heating wires and at least two bus bars which connect end portions of the heating wires such that electric power is supplied to the heating wires;
a first antenna wire disposed along at least three sides of a perimeter of the defogger and configured to receive radio waves in a first frequency band;
a second antenna wire which is disposed in a peripheral region of the defogger and configured to receive radio waves in a second frequency band which is higher in frequency than the first frequency band; and
an amplification portion configured to synthesize and amplify a first reception signal received by the first antenna wire and a second reception signal received by the second antenna wire, and
wherein the glass antenna has no choke coil that blocks a signal of the first frequency band between a body of the vehicle and the defogger,
the first antenna wire is an amplitude modulation (AM) antenna wire and is disposed at least a first distance from the defogger, the first distance being a shortest distance between the AM antenna wire and the defogger,
the second antenna wire is a frequency modulation (FM) antenna wire and is disposed at a second distance from the defogger such that the FM antenna wire is capacitively coupled with the defogger in a frequency band of FM radio, the second distance being shorter than the first distance, and
the first distance is 40 mm.
2. The back door according to claim 1 , wherein:
the amplification portion is connected to the first antenna wire through a first feeding point and connected to the second antenna wire through a second feeding point; and
at least one of the first feeding point or the second feeding point is disposed in the peripheral region and outside a line along each of the at least two bus bars and an extension line of the line.
3. The back door according to claim 1 , wherein:
the first antenna wire comprises a meander-like conducting wire part; and
an interval between conducting wires in the meander-like conducting wire part is shorter than an interval between the defogger and the first antenna wire.
4. The back door according to claim 3 , wherein:
the interval between the conducting wires in the meander-like conducting wire part is determined such that the conducting wires are capacitively coupled with each other in the first frequency band.
5. A glass antenna for use in a back door made from resin to be openably and closably attached to a rear portion of a vehicle, the glass antenna comprising:
a defogger comprising a plurality of heating wires and at least two bus bars which connect end portions of the heating wires such that electric power is supplied to the heating wires;
a first antenna wire disposed along at least three sides of a perimeter the defogger, so as to receive radio waves in a first frequency band;
a second antenna wire which is disposed in a peripheral region of the defogger and configured to receive radio waves in a second frequency band which is higher in frequency than the first frequency band; and
an amplification portion configured to synthesize and amplify a first reception signal received by the first antenna wire and a second reception signal received by the second antenna wire,
wherein the glass antenna has no choke coil that blocks a signal of the first frequency band between a body of the vehicle and the defogger,
the first antenna wire is an amplitude modulation (AM) antenna wire and is disposed at least a first distance from the defogger, the first distance being a shortest distance between the AM antenna wire and the defogger,
the second antenna wire is a frequency modulation (FM) antenna wire and is disposed at a second distance from the defogger such that the FM antenna wire is capacitively coupled with the defogger in a frequency band of FM radio, the second distance being shorter than the first distance, and
the first distance is 40 mm.
6. The back door according to claim 2 , wherein:
the first feeding point is disposed in the peripheral region and outside a line along each of the at least two bus bars and an extension line of the line.
7. The back door according to claim 6 , wherein:
the second feeding point is disposed in the peripheral region and outside a line along each of the at least two bus bars and an extension line of the line.
8. The back door according to claim 7 , wherein:
the second feeding point is disposed in a position closer to the defogger than the first feeding point.
9. The glass antenna according to claim 5 , wherein:
the amplification portion is connected to the first antenna wire through a first feeding point and connected to the second antenna wire through a second feeding point; and
at least one of the first feeding point and the second feeding point is disposed in the peripheral region and outside a line along each of the at least two bus bars and an extension line of the line.
10. The glass antenna according to claim 9 , wherein:
the first feeding point is disposed in the peripheral region and outside a line along each of the at least two bus bars and an extension line of the line.
11. The glass antenna according to claim 10 , wherein:
the second feeding point is disposed in the peripheral region and outside a line along each of the at least two bus bars and an extension line of the line.
12. The glass antenna according to claim 11 , wherein:
the second feeding point is disposed in a position closer to the defogger than the first feeding point.
13. The glass antenna according to claim 5 , wherein:
the first antenna wire comprises a meander-like conducting wire part; and
an interval between conducting wires in the meander-like conducting wire part is shorter than an interval between the defogger and the first antenna wire.
14. The glass antenna according to claim 13 , wherein:
the interval between the conducting wires in the meander-like conducting wire part is determined such that the conducting wires are capacitively coupled with each other in the first frequency band.